Thinking like an engineer

Learn

What you’ll learn

• The engineering design process used by real engineering teams
• Why “test, then improve” beats “get it perfect first”
• Habits that save hours of frustration

The design process

1. Ask. What’s the problem? What must the robot do? What are the limits (budget, size, time, parts)?
2. Imagine. Brainstorm several ideas. Don’t judge yet.
3. Plan. Pick one idea. Sketch it. List parts. Write the steps.
4. Build. Make the simplest version that could work (a prototype).
5. Test. Does it do the job? Measure, don’t guess.
6. Improve. Change one thing at a time, then test again.

Then go back around. Real robots go through this loop dozens of times. Each trip around is called an iteration.

Requirements and constraints

Before building, write two short lists:

• Requirements (must do): “Follow a black line 2 cm wide. Finish the track in under 30 seconds.”
• Constraints (limits): “Fit in a 20 × 20 cm box. Cost under $40. Use AA batteries.”

Clear requirements tell you when you’re done.

Habits of good builders

• Start small. Get one LED blinking before wiring ten sensors.
• Change one thing at a time. If you change three things and it works, you don’t know which one fixed it.
• Keep a build log. Write down what you tried and what happened. Photos help.
• Expect failure. A failed test isn’t a mistake; it’s information.
• Ask for help with evidence. “It doesn’t work” is hard to help with. “The left motor spins but the right doesn’t, here’s my wiring photo” is easy.

Tip

When something breaks, check the boring things first: Is it powered? Is the battery charged? Is that wire actually plugged in?

Examples

Example: a line follower’s build log

Iteration	Change	Result	What we learned
1	First build, speed 80%	Leaves the line on curves	Too fast for the sensors to react
2	Speed 50% (only change)	Follows the line, 31 s lap	Speed was the problem
3	Sensors moved 2 cm further forward	Follows the line, 27 s lap	Sensors that see further ahead react sooner
4	Speed 65%	Follows the line, 22 s lap	With better sensors it can go faster

One change per iteration made it clear what each change did.

Example: requirements and constraints

Requirements: carry a 50 g load 2 m along a line; finish in under 20 s; stop at the end. Constraints: maximum 15 × 15 cm; budget $30; must use AA batteries.

Practice

Try it

Design challenge (no electronics needed): using paper, tape and up to 10 straws, build a tower that holds a phone 20 cm off the table. Go through at least two iterations and write down what you changed and why.

Write the requirementsEasy

Write two requirements and two constraints for a robot that delivers a pencil across a desk. Requirements: carry one pencil 1 m; stop at the far edge without falling. Constraints: fit in a shoebox; use parts from one starter kit.

One variable at a timeMedium

Your robot misses turns. You suspect speed, sensor position and battery level. Plan three tests that change one thing each. Test 1: fresh batteries, same speed and sensors. Test 2: same batteries, lower speed. Test 3: same batteries and speed, sensors moved forward. Record lap time and misses for each.

Iterate in the simulatorHard

Open the robot simulator line track. Run three iterations of the line follower, changing only the speed each time (30, 50, 70). Record lap times and which ones lose the line. Use the starter code and change the numbers in motors(50, 50).

Quick check

1. Your robot works after you changed the wheels, the code and the battery at once. What is the problem?

Nothing, it worksYou don’t know which change fixed itYou used too many batteriesRobots should never be changed

2. "Must fit inside a 20 × 20 cm box" is a…

RequirementConstraintPrototypeIteration

3. What is a prototype?

The final productA simple early version built to test an ideaA type of sensorA safety rule

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